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Researchers at the Carnegie Institution of Washington (Washington DC, USA) have managed to make a remarkable alloy of hydrogen and oxygen from water! They used X-rays to dissociate water at high pressure to form a solid mixture, that is, an alloy, of molecular oxygen (O2) and molecular hydrogen (H2).

The researchers placed some water under an extremely high pressure, about 170,000 atmospheres (17 Gigapascals), using a diamond anvil and then beamed high-energy X-rays at the water. Nearly all the water molecules split and reformed as a solid alloy of O2 and H2. The X-rays are key to cleaving the O—H bonds in water. Without it, the water remains as a high-pressure form of ice known as ice VII. Ice VII is one of at least 15 kinds of ice that exist under various high pressure and variable temperature conditions.

Russell Hemley of the Carnegie Institution of Washington said "we managed to hit on just the right level of X-ray energy input. Any higher, and the radiation tends to pass right through the sample. Any lower, and the radiation is largely absorbed by the diamonds in our pressure apparatus."

The researchers subjected the alloy to a range of pressures and temperatures, and also bombardment with X-ray and laser radiation. Provided the alloy is kept at about 10,000 times atmospheric pressure at sea level (1 Gigapascal), it withstands the treatment. Although clearly a crystalline solid, more experiments are needed to determine the alloy's precise crystal structure.

"The new radiation chemistry at high pressure was surprising," said Wendy Mao of the Los Alamos National Laboratory in the USA. "The new alloy containing the incompatible oxygen and hydrogen molecules will be a highly energetic material." An explosive alloy!